Similar to X_Window_System

HP Serviceguard

Windows Services for UNIX

Name Service Switch

Network File System

Nm (Unix)

IBM High Availability Cluster Multiprocessing

Procfs

Setuid

Single UNIX Specification

STREAMS

Termcap

Terminfo

Tz database

Udev

UNIX System III

UNIX System V

The UNIX-HATERS Handbook

Unix-like

Unix wars

List of POSIX commands

XFS

Xinetd

ZFS

Interix

Open system (computing)

Virtual console